This invention relates generally to a recording and reproducing device in which a tape is wound or extended around a cylinder over a wide angle, and, more particularly, to a tape guide mechanism for such a recording and reproducing device which prevents opposed tape surfaces, disposed in a vicinity of tape guides adjacent to a tape entrance side and a tape exit side of the cylinder, from contacting each other, and which ensures a stable travel of the tape.
Conventionally, in a magnetic recording and, more reproducing device of the rotary head-type (hereinafter referred to as "VTR") and particularly, to a VTR with an integral camera, a system has been proposed in which, in order to obtain a compact and lightweight construction of the device and also to achieve the compatibility (which enables the use of the same format) of this device with other conventional devices, the reduction of the diameter of the cylinder is achieved by increasing the angle of winding of a tape around the cylinder.
For example, Japanese Patent Unexamined Publication No. 58-101579 discloses a small-diameter cylinder system for a VTR of the .beta. type. In this technique, one-head system is adopted for the purpose of reducing the diameter of the cylinder, and in order to obtain the same format as that of a conventional two-head system in which the angle of winding of a tape around a cylinder is 180.degree., the angle of winding of a tape around the cylinder is increased or widened to 300.degree.. In this case, since the rotational frequency of the cylinder is 60 r.p.s., a vertical scanning speed of the camera is unaltered; however, since the angle of winding of the tape around the cylinder is as small as 300.degree./360.degree., an effective horizontal scanning must be completed during a period corresponding to 300.degree., and signals are recorded with the compression of the time performed about 20% in the horizontal direction. Recently, there has been an increasing demand for VTRs with an integral camera, and therefore the device tends to become more and more compact and, lightweight, and in order to meet a demand for a low cost construction now attainable by a rapid development of memories, there have been proposed small-diameter cylinder systems capable of recording and reproduction which incorporate memories specially designed for compressing and expanding the horizontal scanning speed.
In the above system, in order to achieve a more compact and lightweight construction of the device, it is necessary to reduce the number of the memories as much as possible so as to achieve the low cost design, and it is also necessary to reduce the diameter of the cylinder as much as possible, in which case the tape winding angle is required to be as close to 360.degree. as possible.
As shown in FIG. 7, a cassette 2 contains a magnetic tape 1 wound on a supply reel 2a and a take-up reel 2b. The magnetic tape 1 is wound around the cylinder 3 over an angle of not less than 300.degree., and therefore, as shown in FIG. 8 in the loading-completed condition, that portion of the tape 1 disposed in a tape path 1a extending between first and second guides 5 and 7 at the entrance side of the cylinder 3 is very close, as shown in FIG. 9, to that portion of the tape 1 disposed in a tape path 1b extending between first and second guides 6 and 8 at the exit side of the cylinder 3.
A first problem with the above-described system resides in the fact that, in the tape loading-completed condition, the guides 5 and 6 as well as the guides 7 and 8 are disposed very close to each other at the entrance side and exit side of the cylinder 3. In this condition, when the tape 1 is in a stop mode, the tension of the tape 1 is reduced, so that the tape 1 is loosened. As a result, the opposed portions of the tape 1 disposed respectively in the tape paths 1a and 1b are brought into contact with each other.
Yet another problem arises in that, even when the tape 1 is subjected to a predetermined tension during a travel thereof, the distribution of the tension in the direction of the width of the tape 1 may become uneven because of irreguralities of mounting of the guides, in which case the tape 1 travels with its upper edge portion loosened. As a result, the opposed portions of the tape 1 respectively disposed in the tape paths 1a and 1b are brought into contact with each other, as in the stop mode.